If you try to reset a password from a user via ID Vault you get the error message "Error: File cannot be created" how can this be solved?

This error might indicate a broken ID Vault replica on the server which you are using at the moment. To solve the issue, remove the replica via the ID Vault management tools (do not delete and recreate the replica by hand), wait some minutes until the *.nsf is removed from the server, then re-add it via the ID Vault management tools. Let the server sync the replica with other servers and try the reset again.